package com.carefree.common.excel;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Writer;
import java.util.Calendar;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

import org.apache.poi.ss.usermodel.DateUtil;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

/** 
 * 抽象excel2007读入器，先构建.xlsx一张模板，改写模板中的sheet.xml,使用这种方法 
 * 写入.xlsx文件，不需要太大的内存 
 * 
 */  
public abstract class AbstractExcel2007Writer {  
      
    private SpreadsheetWriter sw;  
  
    /** 
     * 写入电子表格的主要流程 
     * @param fileName 
     * @throws Exception 
     */  
    public void process(String fileName) throws Exception{  
        // 建立工作簿和电子表格对象  
        XSSFWorkbook wb = new XSSFWorkbook();  
        XSSFSheet sheet = wb.createSheet("sheet1");  
        // 持有电子表格数据的xml文件名 例如 /xl/worksheets/sheet1.xml  
        String sheetRef = sheet.getPackagePart().getPartName().getName();  
  
        // 保存模板  
        FileOutputStream os = new FileOutputStream("template.xlsx");  
        wb.write(os);  
        os.close();  
          
        // 生成xml文件  
        File tmp = File.createTempFile("sheet", ".xml");  
        Writer fw = new FileWriter(tmp);  
        sw = new SpreadsheetWriter(fw);  
        generate();  
        fw.close();  
          
        // 使用产生的数据替换模板  
        File templateFile = new File("template.xlsx");  
        FileOutputStream out = new FileOutputStream(fileName);  
        substitute(templateFile, tmp, sheetRef.substring(1), out);  
        out.close();  
        //删除文件之前调用一下垃圾回收器，否则无法删除模板文件  
        System.gc();  
        // 删除临时模板文件  
        if (templateFile.isFile()&&templateFile.exists()){  
            templateFile.delete();  
        }  
    }  
  
    /** 
     * 类使用者应该使用此方法进行写操作 
     * @throws Exception 
     */  
    public abstract void generate() throws Exception;  
  
    public void beginSheet() throws IOException {  
        sw.beginSheet();  
    }  
  
    public void insertRow(int rowNum) throws IOException {  
        sw.insertRow(rowNum);  
    }  
  
    public void createCell(int columnIndex, String value) throws IOException {  
        sw.createCell(columnIndex, value, -1);  
    }  
  
    public void createCell(int columnIndex, double value) throws IOException {  
        sw.createCell(columnIndex, value, -1);  
    }  
  
    public void endRow() throws IOException {  
        sw.endRow();  
    }  
  
    public void endSheet() throws IOException {  
        sw.endSheet();  
    }  
  
    /** 
     * 
     * @param zipfile the template file 
     * @param tmpfile the XML file with the sheet data 
     * @param entry the name of the sheet entry to substitute, e.g. xl/worksheets/sheet1.xml 
     * @param out the stream to write the result to 
     */  
    private static void substitute(File zipfile, File tmpfile, String entry,  
            OutputStream out) throws IOException {  
        ZipFile zip = new ZipFile(zipfile);  
        ZipOutputStream zos = new ZipOutputStream(out);  
  
        @SuppressWarnings("unchecked")  
        Enumeration<ZipEntry> en = (Enumeration<ZipEntry>) zip.entries();  
        while (en.hasMoreElements()) {  
            ZipEntry ze = en.nextElement();  
            if (!ze.getName().equals(entry)) {  
                zos.putNextEntry(new ZipEntry(ze.getName()));  
                InputStream is = zip.getInputStream(ze);  
                copyStream(is, zos);  
                is.close();  
            }  
        }  
        zos.putNextEntry(new ZipEntry(entry));  
        InputStream is = new FileInputStream(tmpfile);  
        copyStream(is, zos);  
        is.close();  
        zos.close();  
    }  
  
    private static void copyStream(InputStream in, OutputStream out)  
            throws IOException {  
        byte[] chunk = new byte[1024];  
        int count;  
        while ((count = in.read(chunk)) >= 0) {  
            out.write(chunk, 0, count);  
        }  
    }  
  
    /** 
     * 在写入器中写入电子表格 
     *  
     */  
    public static class SpreadsheetWriter {  
        private final Writer _out;  
        private int _rownum;  
        private static String LINE_SEPARATOR = System.getProperty("line.separator");  
  
        public SpreadsheetWriter(Writer out) {  
            _out = out;  
        }  
  
        public void beginSheet() throws IOException {  
            _out.write("<?xml version=\"1.0\" encoding=\"GB2312\"?>"  
                            + "<worksheet xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\">");  
            _out.write("<sheetData>"+LINE_SEPARATOR);  
        }  
  
        public void endSheet() throws IOException {  
            _out.write("</sheetData>");  
            _out.write("</worksheet>");  
        }  
  
        /** 
         * 插入新行 
         * 
         * @param rownum 以0开始 
         */  
        public void insertRow(int rownum) throws IOException {  
            _out.write("<row r=\"" + (rownum + 1) + "\">"+LINE_SEPARATOR);  
            this._rownum = rownum;  
        }  
  
        /** 
         * 插入行结束标志 
         */  
        public void endRow() throws IOException {  
            _out.write("</row>"+LINE_SEPARATOR);  
        }  
  
        /** 
         * 插入新列 
         * @param columnIndex 
         * @param value 
         * @param styleIndex 
         * @throws IOException 
         */  
        public void createCell(int columnIndex, String value, int styleIndex)  
                throws IOException {  
            String ref = new CellReference(_rownum, columnIndex)  
                    .formatAsString();  
            _out.write("<c r=\"" + ref + "\" t=\"inlineStr\"");  
            if (styleIndex != -1)  
                _out.write(" s=\"" + styleIndex + "\"");  
            _out.write(">");  
            _out.write("<is><t>"+XMLEncoder.encode(value)+"</t></is>");  
            _out.write("</c>");  
        }  
  
        public void createCell(int columnIndex, String value)  
                throws IOException {  
            createCell(columnIndex, value, -1);  
        }  
  
        public void createCell(int columnIndex, double value, int styleIndex)  
                throws IOException {  
            String ref = new CellReference(_rownum, columnIndex)  
                    .formatAsString();  
            _out.write("<c r=\"" + ref + "\" t=\"n\"");  
            if (styleIndex != -1)  
                _out.write(" s=\"" + styleIndex + "\"");  
            _out.write(">");  
            _out.write("<v>" + value + "</v>");  
            _out.write("</c>");  
        }  
  
        public void createCell(int columnIndex, double value)  
                throws IOException {  
            createCell(columnIndex, value, -1);  
        }  
  
        public void createCell(int columnIndex, Calendar value, int styleIndex)  
                throws IOException {  
            createCell(columnIndex, DateUtil.getExcelDate(value, false),  
                    styleIndex);  
        }  
    }  
}